One afternoon last December, an assassin on board a K.L.M. flight from Mexico City arrived at Amsterdam’s Schiphol Airport. This was not a business trip: the killer, who was thirty-three, liked to travel, and often documented his journeys around Europe on Instagram. He wore designer clothes and a heavy silver ring in the shape of a grimacing skull. His passport was an expensive fake, and he had used it successfully many times. But, moments after he presented his documents to Dutch customs, he was arrested. The U.S. Drug Enforcement Administration had filed a Red Notice with Interpol—an international arrest warrant—and knew that he was coming. Only after the Dutch authorities had the man in custody did they learn his real identity: José Rodrigo Arechiga, the chief enforcer for the biggest drug-trafficking organization in history, Mexico’s Sinaloa cartel.

To work in the Mexican drug trade is to have a nickname, and Arechiga went by the whimsically malevolent handle El Chino Ántrax. He supervised the armed wing of the Sinaloa—a cadre of executioners known as Los Ántrax—and coördinated drug shipments for the cartel’s leader, Joaquín Guzmán Loera, who was known as El Chapo, or Shorty. Arechiga was a narcotraficante of the digital age, bantering with other criminals on Twitter and posting snapshots of himself guzzling Cristal, posing with exotic pets, and fondling a gold-plated AK-47. Guzmán, who is fifty-seven, typified an older generation. Obsessively secretive, he ran his multibillion-dollar drug enterprise from hiding in Sinaloa, the remote western state where he was born, and from which the cartel takes its name. The Sinaloa cartel exports industrial volumes of cocaine, marijuana, heroin, and methamphetamine to America; it is thought to be responsible for as much as half the illegal narcotics that cross the border every year. Guzmán has been characterized by the U.S. Treasury Department as “the world’s most powerful drug trafficker,” and after the killing of Osama bin Laden, three years ago, he became perhaps the most wanted fugitive on the planet. Mexican politicians promised to bring him to justice, and the U.S. offered a five-million-dollar reward for information leading to his capture. But part of Guzmán’s fame stemmed from the perception that he was uncatchable, and he continued to thrive, consolidating control of key smuggling routes and extending his operation into new markets in Europe, Asia, and Australia. According to one study, the Sinaloa cartel is now active in more than fifty countries.

On several occasions, authorities had come close to catching Guzmán. In 2004, the Mexican Army descended on a dusty ranch in Sinaloa where he was holed up, but he had advance warning and fled along a rutted mountain track in an all-terrain vehicle. Three years later, Guzmán married a teen-age beauty queen named Emma Coronel and invited half the criminal underworld of Mexico to attend the ceremony. The Army mobilized several Bell helicopters to crash the party; the troops arrived, guns drawn, to discover that Guzmán had just departed. American authorities have no jurisdiction to make arrests in Mexico, so whenever D.E.A. agents developed fresh intelligence about Guzmán’s whereabouts all they could do was feed the leads to their Mexican counterparts and hope for the best. In Washington, concerns about the competence of Mexican forces mingled with deeper fears about corruption. A former senior Mexican intelligence official told me that the cartel has “penetrated most Mexican agencies.” Was Guzmán being tipped off by an insider? After a series of near-misses in which Chapo foiled his pursuers by sneaking out of buildings through back doors, officials at the U.S. Embassy in Mexico City took to joking, bitterly, that there is no word in Spanish for “surround.”

Guzmán developed “a Zorro-like reputation,” Gil Gonzalez, who pursued him in Mexico for the D.E.A., told me. In dozens of narcocorridos, the heraldic Mexican ballads that glorify traffickers, singers portrayed Guzmán as a country boy turned cunning bandit who had grown rich but not soft, his cuerno de chivo, or “goat horn”—Mexican slang for an assault rifle with a curved magazine—never far from his side.

Yet Guzmán himself remained maddeningly obscure. Only a few photographs of him circulated publicly. A famous series taken after an arrest in 1993 shows a stocky, dark-eyed, square-jawed young man standing awkwardly in a prison yard; he gazes at the camera with a shyness that seems at odds with his fearsome reputation. Chapo escaped eight years later, and had been on the run ever since. Because he might have had plastic surgery to alter his appearance, the authorities could no longer be sure what he looked like. One narcocorrido captured the predicament: “Only he knows who he is / So go looking for someone / Who looks just like him / Because the real Chapo / You’ll never see again.”

The authorities tried to track Guzmán by monitoring telephone lines. Narcotics smuggling necessitates regular phone communication between farmers and packers, truckers and pilots, accountants and enforcers, street dealers and suppliers. But traffickers at the top of the hierarchy maintain operational security by rarely making calls or sending e-mails. Guzmán was known to use sophisticated encryption and to limit the number of people he communicated with, keeping his organization compartmentalized and allowing subordinates a degree of autonomy, as long as the shipments kept running on time. “I never spoke to him directly,” one former Sinaloa lieutenant told me. “But I knew what he wanted us to do.”

The Sinaloa cartel is sometimes described as a “cellular” organization. Structurally, its network is distributed, and has more in common with a terrorist organization like Al Qaeda than with the antiquated hierarchies of the Cosa Nostra. When the cartel suffers the loss of a major figure like El Chino Ántrax, it can reconstitute itself—but not without a few phone calls among the leadership. At the D.E.A., which taps hundreds of phone lines and e-mail accounts associated with traffickers, the process of applying pressure to a criminal organization and then monitoring furtive attempts at outreach is known as “tickling the wires.” When El Chino Ántrax was arrested in Amsterdam, the cartel was still coping with two other high-level losses: in November, the twenty-three-year-old son of one of Guzmán’s closest associates was arrested while trying to cross the border in Nogales; in December, Mexican troops in a helicopter shot and killed another key cartel enforcer, on a stretch of highway by the Sea of Cortez.

As the cartel attempted to regroup, authorities on both sides of the border intercepted scores of phone calls, texts, and e-mails. They learned that Guzmán would soon be coming to Culiacán, the state capital of Sinaloa, for a meeting with his sons Alfredo and Iván—ascendant traffickers who were both close friends of El Chino Ántrax. The D.E.A. presented an intelligence dossier to authorities in Mexico, and in mid-January a special-forces unit of commandos from the Mexican Marines, or SEMAR, began to assemble at a forward operating base near the resort town of Los Cabos, along the southern tip of the Baja Peninsula. The marines, who are the Mexican equivalent of Navy SEALs, were joined by a small group of American advisers. Mexican authorities code-named the mission Operation Gargoyle. Its object was to capture Guzmán.

According to the Dallas Morning News, the government of Mexico’s President Enrique Peña Nieto informed the marines and their American partners that they would have approximately three weeks to bring down the drug lord. A U.S. official involved in planning the operation told me that this was true. Fighting drug traffickers in Mexico has become a matter of triage, and the SEMAR unit was soon to be redeployed to battle another cartel, the Knights Templar, in the restive state of Michoacán. (Eduardo Sánchez, the chief spokesman for the government of Mexico, denied that any such time limit was in place. “There was no window,” he said.)

As the marines and their advisers moved into Los Cabos, they tried not to attract attention. A battleship anchored off the coast was used as a decoy, so that curious observers might conclude that the sudden influx of commandos was part of a standard naval exercise. But one reason that Guzmán had remained at large so long was his unparalleled network of informants. One person involved in the operation told me, “As soon as we landed, he knew.”

Guzmán had always been a master of escape. Born in the mountain village of La Tuna, in Mexico’s wild and craggy Sierra Madre Occidental, he was the oldest child of a subsistence farmer who dabbled in the drug trade. For generations, Sinaloan ranchers had cultivated cannabis and opium, and children were taken out of elementary school to assist in the harvest. Guzmán left school for good in third grade, and in the seventies, in spite of his illiteracy, he became an apprentice to two drug chieftains: Amado Carrillo Fuentes, who owned a fleet of airplanes and was known as the Lord of the Skies; and Miguel Ángel Félix Gallardo, a police officer turned drug baron, who ran the Guadalajara cartel and was known as El Padrino—the Godfather.

Guzmán started as a kind of air-traffic controller, coördinating cocaine flights from Colombia. But he was clever and aggressive, and quickly began to acquire power. One night in November, 1992, Guzmán’s henchmen massacred six people at a crowded discothèque in Puerto Vallarta. They severed the telephone lines so that nobody could call for help, then walked inside and opened fire on the dance floor. The targets were Tijuana-based traffickers whom Guzmán was challenging for control of the lucrative smuggling routes through Baja California. They were in the bathroom when the shooting started, and fled without being harmed. The next spring, the traffickers arranged for their own hit men to murder Guzmán at the international airport in Guadalajara. As gunfire erupted, Guzmán scrambled out of his vehicle and crawled to safety. Seven people were killed, including Archbishop Juan Jesús Posadas Ocampo. (The gunmen apparently mistook him for Guzmán.) Ocampo’s murder caused a political uproar, and it was not long before Guzmán, who had gone into hiding, was picked up by authorities in Guatemala and turned over to Mexico. He was sentenced to twenty years in prison, on charges of conspiracy, drug trafficking, and bribery, and ended up in Puente Grande, in Jalisco, which was considered one of the most secure prisons in Mexico.

Behind bars, Guzmán consolidated both his empire and his reputation. He bought off the prison staff and enjoyed a life of relative luxury: he conducted business by cell phone, orchestrated regular visits from prostitutes, and threw parties for favored inmates that featured alcohol, lobster bisque, and filet mignon. While he was there, the Mexican attorney general’s office subjected him to psychological interviews. The resulting criminal profile noted that he was “egocentric, narcissistic, shrewd, persistent, tenacious, meticulous, discriminating, and secretive.”

One day in January, 2001, a prison administrator pulled aside a makeshift curtain that Guzmán had draped across the entrance to his cell and shouted, “He’s escaped!” A subsequent investigation determined that Guzmán had hidden in a laundry cart pushed by a paid accomplice. But many in Mexico speculate that he didn’t have to bother with subterfuge. Guzmán controlled Puente Grande so thoroughly by the time of his exit that he might as well have walked out the front door. Criminal charges were eventually brought against seventy-one people who worked at the prison, including the warden.

If Chapo’s escape suggested that the Mexican political system had been corroded by drug money, his subsequent years as a fugitive did not diminish this impression. He retreated to Sinaloa and expanded his operations, launching violent turf wars with rival cartels over control of prized entry points along the U.S. border. The sociologist Diego Gambetta, in his 1993 book “The Sicilian Mafia,” observes that durable criminal enterprises are often woven into the social and political fabric, and part of their “intrinsic tenacity” is their ability to offer certain services that the state does not. Today on the streets of Culiacán you see night clubs, fortified villas, and an occasional Lamborghini. Chapo and other drug lords have invested and laundered their proceeds by buying hundreds of legitimate businesses: restaurants, soccer stadiums, day-care centers, ostrich farms. Juan Millán, the former state governor of Sinaloa, once estimated that sixty-two per cent of the state’s economy is tied up with drug money. Sinaloa remains poor, however, and Badiraguato, the municipality containing Guzmán’s home village, is one of the most desperate areas in the state. There had always been some sympathy for the drug trade in Sinaloa, but nothing deepens sympathy like charity and bribes. Eduardo Medina Mora, Mexico’s Ambassador in Washington, described Guzmán’s largesse in the state: “You are financing everything. Baptisms. Infrastructure. If someone gets sick, you provide a little plane. So you have lots of local support, because you are Santa Claus. And everybody likes Santa Claus.”

Mexico’s municipal police were poorly trained, poorly paid, and poorly equipped, rendering them susceptible to bribery. “In practical terms, organized crime literally privatized the municipal police forces across many parts of the country,” one senior Mexican official told me. Guzmán’s influence over the public sector was not confined to law enforcement. Last year, a former bodyguard for the current governor of Sinaloa, Mario López Valdez, released a series of YouTube videos in which he described accompanying López Valdez, who had just taken office, on a trip to meet with Guzmán. In one video, the bodyguard played a recorded conversation in which the Governor appeared to instruct his subordinates not to antagonize the Sinaloa cartel—and, instead, to crack down on its rivals. López Valdez insisted that the recording was doctored. Last August, the bodyguard was discovered beside a road in Sinaloa. He had been decapitated.

As long as Guzmán remained in the mountains, the inhospitable terrain and the allegiance of locals appeared to guarantee his safety. In 2009, Dennis Blair, President Barack Obama’s national intelligence director, met with Guillermo Galván, who was then Mexico’s Secretary of Defense. Galván told him that everybody knew, roughly, where Guzmán was. The challenge was taking him into custody. According to a diplomatic cable that was later released by WikiLeaks, Galván explained that Guzmán was believed to move among a dozen or so ranches, and to be protected by up to three hundred armed men. The peaks of the Sierra Madre Occidental are steep and jagged, and the roads that vein their contours often taper to a single dirt track. An armored convoy would be spotted by Guzmán’s lookouts well before it arrived at its destination. And if a Blackhawk helicopter was dispatched to attack his outpost he would hear it thundering across the valley from miles out, leaving plenty of time to flee.

More recently, however, intelligence collected by Mexican authorities and the D.E.A. indicated that Guzmán might be changing his habits. There is a saying in the Mexican drug trade that it is better to live one good year than ten bad ones. Many young men enter the industry expecting to enjoy a decadent life for a short time before being incarcerated or killed. Young narcos behave recklessly: they go to night clubs, they race Bentleys, and they post pictures of themselves online with their co-conspirators (and with the occasional dead body). The only traffickers in Sinaloa who beat the odds are those who are content to follow a more austere life in the mountains. Until lately, Guzmán had taken that approach. But because he was tired, or married to a much younger woman, or overconfident of his ability to escape, Guzmán began spending time in Culiacán and other cities. “Here’s a guy who has made hundreds of millions of dollars in the drug trade, and he’s living like a pauper up in the mountains,” Mike Vigil, a former D.E.A. agent who worked in Mexico for many years, told me. “He likes the fiestas. He likes the music. He likes to dance.” Another law-enforcement official speculated that, though Guzmán was accustomed to a rustic life, Emma Coronel was not. “She’s not much of a mountain person,” he said, adding that they had twin daughters, and, even though Guzmán was a fugitive, his wife was adamant that he be present in the girls’ lives: “She would go out of her way to maintain that family life.”

Guzmán had other weaknesses. “He loves the gourmet food,” a D.E.A. official told me. From time to time, he would be spotted at an elegant restaurant in Sinaloa or in a neighboring state. The choreography was always the same. Diners would be startled by a team of gunmen, who would politely but firmly demand their telephones, promising that they would be returned at the end of the evening. Chapo and his entourage would come in and feast on shrimp and steak, then thank the other diners for their forbearance, return the telephones, pick up the tab for everyone, and head off into the night.

It has been reported, erroneously, that Guzmán used a statellite phone; in fact, his favored communication device was the BlackBerry. Like many narcos, he was suspicious of satellite phones, because most of the companies that manufacture them are American and the devices are relatively easy for law-enforcement officials to compromise. But the BlackBerry is made by a Canadian company, and Guzmán felt more comfortable using one. This trust was misplaced: by early 2012, the D.E.A. had homed in on Guzmán’s BlackBerry, and could not only monitor his communications but also use geolocation technology to triangulate his signal.

That February, the agency confirmed that Guzmán had travelled to Los Cabos for a liaison with a prostitute. He had been married at least three times, and he had relationships with many mistresses; nevertheless, he appears to have had an unflagging appetite for paid companionship. (Numerous current and former officials noted Guzmán’s prodigious consumption of Viagra. “He ate it like candy,” one said.) The D.E.A. agents who monitored his e-mails and texts marvelled at the extent to which his communications seemed focussed not on managing his multinational empire but on juggling the competing demands of his wife, his ex-wives (with whom he remained cordial), his girlfriends, and his paid consorts. “It was like ‘Peyton Place,’ ” a former law-enforcement official who kept track of the communications told me. “It was a non-stop deal.”

After authorities traced the BlackBerry signal to a mansion on a cul-de-sac in a wealthy enclave near the coast, Mexican troops burst through the front door of the building. Whether or not Guzmán had been alerted in advance remains unclear, but he had enough time to sneak out the back of the property; he went to an adjacent resort, where he blended into a crowd of vacationers before moving on. Over the next three days, the authorities pursued him as he moved around the city, desperately trying to arrange an escape route to the mountains.

At one point during the chase, Guzmán must have realized that his BlackBerry had been compromised, and decided to turn this setback to his advantage. He met up with a subordinate and gave him the BlackBerry. Someone involved in the operation said of Guzmán, “He took us for a ride.” The authorities, unaware of the handoff, chased the signal around Los Cabos, until they finally pounced on the sacrificial subordinate. While they were occupied with arresting him, Chapo made it into the desert, where a private plane picked him up and flew him back to the safety of the Sierra Madre.

“He changed it up after Los Cabos,” one U.S. law-enforcement official told me, adding a line worthy of a narcocorrido: “He’s an illiterate son of a bitch, but he’s a street-smart motherfucker.” Rather than switch BlackBerrys, as he had done in the past, Guzmán now appeared to have stopped communicating altogether.”